单项选择题

A strong wind can be a dangerous thing—sometimes it is powerful enough to knock you down. But to some plants, the wind is a source (来源) of new life, carrying them or their spores (孢子) thousands of miles.
A NASA satellite called QuikSCAT has discovered highways of wind over the Earth’s oceans. Scientists believe these invisible roads may explain why many nonflowering plants grow where they do.
The satellite is able to send microwaves (微波) from space to the surface of the ocean. The pattern of signals (信号) that come back shows which way the winds are blowing.
Using this data, the scientists studied a group of islands in the southern hemisphere (半球), near Antarctica. Winds tend to blow anticlockwise (逆时针) in this area, but there are lots of local differences.
When the researchers compared these local patterns to botanical (植物学) data, they found that the wind had an important effect on where species (品种) of mosses (苔), lichens (地衣), and other nonflowering plants grow.
For example, Bouvet Island and Heard Island share 30 percent of their moss species, 29 percent of liverworts (叶苔), and 32 percent of lichens—even though they are 4,430 kilometers apart. However Gough Island and Bouvet Island, separated by just 1,860 kilometers of sea, share only 16 percent of mosses and 17 percent of liverworts. They have no lichens in common.
Ferns (蕨类植物) and flowering plants don’t travel as well in the wind, so they don’t show the same kinds of distribution (分布) patterns. This passage is about ______.